JP4067683B2 - How to prevent tank lift during installation - Google Patents

How to prevent tank lift during installation Download PDF

Info

Publication number
JP4067683B2
JP4067683B2 JP07974699A JP7974699A JP4067683B2 JP 4067683 B2 JP4067683 B2 JP 4067683B2 JP 07974699 A JP07974699 A JP 07974699A JP 7974699 A JP7974699 A JP 7974699A JP 4067683 B2 JP4067683 B2 JP 4067683B2
Authority
JP
Japan
Prior art keywords
tank
installation work
pipe
water
water level
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP07974699A
Other languages
Japanese (ja)
Other versions
JP2000273920A (en
Inventor
隆 船岡
章 今川
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Plant Technologies Ltd
Original Assignee
Hitachi Plant Technologies Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Plant Technologies Ltd filed Critical Hitachi Plant Technologies Ltd
Priority to JP07974699A priority Critical patent/JP4067683B2/en
Publication of JP2000273920A publication Critical patent/JP2000273920A/en
Application granted granted Critical
Publication of JP4067683B2 publication Critical patent/JP4067683B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Landscapes

  • Sewage (AREA)

Description

【0001】
【発明の属する技術分野】
本発明は、設置工事中のタンクの浮き上がり防止方法に関し、特に、タンクの設置工事中にタンク周辺の水位が上昇したときに、タンクの浮き上がりを簡易に防止するための設置工事中のタンクの浮き上がり防止方法に関するものである。
【0002】
【従来の技術】
従来、平面形状が円形や角形のコンクリート製や金属製の下水処理槽等の大形のタンク類(本明細書において、単に、「タンク」という。)の設置工事中に、大雨やダムの放水等によりタンク周辺の水位が上昇すると、タンクに浮力が働き、タンクが浮き上がる事故が発生して、多大な損害を被ることがあった。
【0003】
これを防止するために、タンクの設置工事の期間中、常時タンク内に水張りを行うことにより、タンク周辺の水位の上昇によってタンクが浮き上がらないようにしたり、タンク周辺の水位の上昇が予想される場合に、タンク内に水張りを行うことにより、タンクの浮き上がりを防止することが行われていた。
【0004】
【発明が解決しようとする課題】
これによって、タンクの浮き上がりを防止することができるものの、常時タンク内に水張りを行うようにすると、タンクにポンプ等の各種機械設備の据付作業を行う際の支障となり、その都度、タンク内の水を抜き、ドライな状態にして上記の据付作業を行った後、再度、水張りを行う必要があり、作業効率が低下するという問題があった。
【0005】
一方、タンク周辺の水位の上昇が予想される場合に、タンク内に水張りを行うようにすると、水張り及び水抜きに手数を要し、作業効率が低下するだけでなく、不測のタンク周辺の水位の上昇に対応することができないという問題があった。
【0006】
本発明は、上記従来のタンクの設置工事の際の問題点に鑑み、作業効率を低下させることなく、タンクの設置工事中にタンク周辺の水位が上昇したときに、タンクの浮き上がりを簡易に防止することができるようにした設置工事中のタンクの浮き上がり防止方法を提供することを目的とする。
【0007】
【課題を解決するための手段】
上記目的を達成するため、本発明の設置工事中のタンクの浮き上がり防止方法は、タンクの底部近傍位置に、端部をタンク外に開放した捨て管を配設し、タンクの設置工事中にタンク周辺の水位が上昇したときに、タンク内に水を流入させるようにする設置工事中のタンクの浮き上がり防止方法において、仕切壁により区画されている隣接する室を連通する貫通管を、設置工事完了後、貫通管の上部に補助管を接続することにより、タンクの一方の室から他方の室に処理液を導入する設備配管として利用できるように配設し、該貫通 管を介して、区画された複数の室の各々に水を流入させるようにすることを特徴とする。
【0008】
この設置工事中のタンクの浮き上がり防止方法は、タンクの底部近傍位置に、端部をタンク外に開放した捨て管を配設し、タンクの設置工事中にタンク周辺の水位が上昇したときに、タンク内に水を流入させるようにする設置工事中のタンクの浮き上がり防止方法において、仕切壁により区画されている隣接する室を連通する貫通管を、設置工事完了後、貫通管の上部に補助管を接続することにより、タンクの一方の室から他方の室に処理液を導入する設備配管として利用できるように配設し、該貫通管を介して、区画された複数の室の各々に水を流入させるようにすることにより、タンクの設置工事中にタンク周辺の水位が上昇しても、これに対応して、タンク内にタンク周辺の水が捨て管を介して流入して、タンク周辺の水位の上昇によってタンクが浮き上がることを、確実に防止することができる。
【0009】
そして、タンク内に捨て管を介して流入したタンク周辺の水を、さらに、貫通管を介して、仕切壁により区画された複数の室の各々に流入させることができ、浮力を生じさせる室をなくすことにより、周辺の水位の上昇によってタンクが浮き上がることを、より確実に防止することができる。
【0010】
【発明の実施の形態】
以下、本発明の設置工事中のタンクの浮き上がり防止方法の実施の形態を図面に基づいて説明する。
【0011】
図1は、本発明の設置工事中のタンクの浮き上がり防止方法を適用するタンクの一実施例を示す。
【0012】
このタンク1は、仕切壁5により複数の室、本実施例においては、ディッチ6と沈澱池7の2室に区画された平面形状が円形の下水処理槽であって、鉄筋コンクリート製の底盤2、側壁3及び天盤9並びに仕切壁5によって構成されている。
【0013】
この場合において、タンク1の側壁3の底部近傍位置に、端部をタンク1外に開放した捨て管4を配設し、タンクの設置工事中にタンク周辺の水位WLが上昇したときに、タンク1内に水を流入させるように構成する。
【0014】
これにより、タンク1の設置工事中にタンク周辺の水位WLが上昇しても、これに対応して、タンク1内にタンク周辺の水が捨て管4を介して流入して、タンク周辺の水位の上昇によってタンク1が浮き上がることを、確実に防止することができるものとなる。
【0015】
そして、本実施例のように、タンク1が仕切壁5により複数の室、すなわち、ディッチ6と沈澱池7に区画されている場合、隣接する室6,7を連通する貫通管8を配設するようにする。
この場合、貫通管8は、捨て管4と、略同じ高さ位置に配設するようにする。
【0016】
これにより、タンク1(ディッチ6)内に捨て管4を介して流入したタンク周辺の水を、さらに、貫通管8を介して、仕切壁5により区画され、捨て管4が設けられていないタンク1の室(沈澱池7)に流入させることができ、浮力を生じさせる室をなくすことにより、周辺の水位の上昇によってタンク1が浮き上がることを、より確実に防止することができるものとなる。
【0017】
タンク1に配設する捨て管4及び貫通管8の数及び管径並びに配設位置等は、タンク1の容量、予想されるタンク周辺の水位の上昇速度等に応じて決定することができる。
【0018】
また、本実施例において、タンク1に配設した捨て管4の設置工事完了後、閉鎖して使用しないが、貫通管8は、上部に補助管8aを接続することにより、ディッチ6から沈澱池7に処理液を導入する設備配管として利用するようにする。
【0019】
このタンク1を地盤10中に設置(構築)するに当たっては、タンク1の側壁3の底部近傍位置に、端部をタンク1外に開放した捨て管4を、タンクの設置工事中にタンク周辺の水位WLが上昇したときに、タンク1内に水が円滑に流入するように配設し、さらに、タンク1が仕切壁5により複数の室、すなわち、ディッチ6と沈澱池7に区画されている場合には、隣接する室6,7を連通する貫通管8を配設して、タンク1(ディッチ6)内に捨て管4を介して流入したタンク周辺の水を、さらに、貫通管8を介して、仕切壁5により区画され、捨て管4が設けられていないタンク1の室(沈澱池7)に流入するようにして、浮力を生じさせる室をなくすことにより、周辺の水位の上昇によってタンク1が浮き上がることを、防止するようにする。
これにより、タンク1内に水張りを行う必要がなくなり、また、不測のタンク周辺の水位の上昇に対応することができ、作業工程の平準化を図ることが可能となり、作業効率を向上することができる。
【0020】
以上、本発明の設置工事中のタンクの浮き上がり防止方法を、ディッチ6と沈澱池7の2室に区画された平面形状が円形のコンクリート製の下水処理槽に適用した例について説明したが、本発明の設置工事中のタンクの浮き上がり防止方法の適用対象は、これに限定されず、平面形状が円形や角形のコンクリート製や金属製の各種用途に用いられる大形のタンク類に広く適用することができる。
【0021】
【発明の効果】
本発明の設置工事中のタンクの浮き上がり防止方法によれば、タンクの底部近傍位置に、端部をタンク外に開放した捨て管を配設し、タンクの設置工事中にタンク周辺の水位が上昇したときに、タンク内に水を流入させるようにする設置工事中のタンクの浮き上がり防止方法において、仕切壁により区画されている隣接する室を連通する貫通管を、設置工事完了後、貫通管の上部に補助管を接続することにより、タンクの一方の室から他方の室に処理液を導入する設備配管として利用できるように配設し、該貫通管を介して、区画された複数の室の各々に水を流入させるようにすることにより、タンクの設置工事中にタンク周辺の水位が上昇しても、これに対応して、タンク内にタンク周辺の水が捨て管を介して流入して、タンク周辺の水位の上昇によってタンクが浮き上がることを、確実に防止することができ、これにより、不測のタンク周辺の水位の上昇に対応することができるとともに、作業工程の平準化を図ることが可能となり、作業効率を低下させることなく、タンクの浮き上がりを簡易に防止することができる。
【0022】
そして、タンク内に捨て管を介して流入したタンク周辺の水を、さらに、貫通管を介して、仕切壁により区画された複数の室の各々に流入させることができ、浮力を生じさせる室をなくすことにより、周辺の水位の上昇によってタンクが浮き上がることを、より確実に防止することができるとともに、仕切壁により区画されている隣接する室を連通する貫通管を、設置工事完了後、貫通管の上部に補助管を接続することにより、タンクの一方の室から他方の室に処理液を導入する設備配管として利用できる
【図面の簡単な説明】
【図1】 本発明の設置工事中のタンクの浮き上がり防止方法を適用したタンクの一例を示す説明図である。
【符号の説明】
1 タンク
2 底盤
3 側壁
4 捨て管
5 仕切壁
6 室(デイッチ)
7 室(沈澱池)
8 貫通管
9 天盤
10 地盤
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for preventing tank lift during installation work, and in particular, when the water level around the tank rises during tank installation work, the tank lift during installation work to easily prevent the tank from rising. It relates to a prevention method.
[0002]
[Prior art]
Conventionally, during installation work of large tanks (simply referred to as “tanks” in this specification) such as concrete and metal sewage treatment tanks with round or square planar shapes, heavy rain and dam discharge If the water level around the tank rises due to such factors as the buoyancy of the tank, an accident in which the tank floats may occur, resulting in considerable damage.
[0003]
In order to prevent this, it is expected that the tank will not rise due to the rise in the water level around the tank or the water level around the tank will rise by constantly filling the tank with water during the tank installation work. In some cases, the tank is prevented from being lifted by filling the tank with water.
[0004]
[Problems to be solved by the invention]
This prevents the tank from rising, but if the tank is always filled with water, it will hinder the installation work of various mechanical equipment such as pumps to the tank. After performing the above installation work in a dry state, there is a problem that it is necessary to perform water filling again, resulting in a reduction in work efficiency.
[0005]
On the other hand, if the water level around the tank is expected to rise, filling the tank with water requires troublesome water filling and draining, which not only reduces work efficiency, but also causes an unexpected water level around the tank. There was a problem that it was not possible to cope with the rise.
[0006]
In view of the problems in the conventional tank installation work, the present invention simply prevents the tank from rising when the water level around the tank rises during the tank installation work without reducing the work efficiency. It is an object of the present invention to provide a method for preventing the tank from being lifted up during installation work.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the tank lifting prevention method during the installation work of the present invention is arranged such that a waste pipe whose end is opened to the outside of the tank is disposed near the bottom of the tank, and the tank is installed during the tank installation work. Completed the installation of a through pipe that connects adjacent chambers partitioned by a partition wall in the tank lift prevention method during installation to allow water to flow into the tank when the surrounding water level rises After that, by connecting an auxiliary pipe to the upper part of the through pipe, it is arranged so that it can be used as equipment piping for introducing the processing liquid from one chamber of the tank to the other chamber , and is partitioned through the through pipe. Water is allowed to flow into each of the plurality of chambers .
[0008]
The tank lift prevention method during the installation work is to install a waste pipe with the end open to the outside of the tank near the bottom of the tank, and when the water level around the tank rises during the tank installation work, In the tank floating prevention method during installation work that allows water to flow into the tank, a through pipe that communicates with the adjacent chambers partitioned by the partition wall is installed on the upper part of the through pipe after the installation work is completed. Is connected so that it can be used as equipment piping for introducing the processing liquid from one chamber of the tank to the other chamber, and water is supplied to each of the partitioned plural chambers through the through pipe. By making it flow, even if the water level around the tank rises during the installation work of the tank, the water around the tank will flow into the tank via the drain pipe in response to this. Due to rising water level That tank from floating Te, can be reliably prevented.
[0009]
Then, the water around the tank that has flowed into the tank through the discard pipe can be further flowed into each of the plurality of chambers partitioned by the partition wall through the through pipe, and a chamber that generates buoyancy is provided. By eliminating it, it is possible to more reliably prevent the tank from floating due to the rise in the surrounding water level.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a tank lifting prevention method during installation work of the present invention will be described below with reference to the drawings.
[0011]
FIG. 1 shows an embodiment of a tank to which the tank lifting prevention method during installation work of the present invention is applied.
[0012]
The tank 1 is a sewage treatment tank having a circular plane shape partitioned into a plurality of chambers by a partition wall 5, in this embodiment, a ditch 6 and a sedimentation basin 7. The side wall 3, the top panel 9, and the partition wall 5 are configured.
[0013]
In this case, a waste pipe 4 having an end opened to the outside of the tank 1 is disposed at a position near the bottom of the side wall 3 of the tank 1, and when the water level WL around the tank rises during the tank installation work, 1 is configured to allow water to flow into it.
[0014]
Thereby, even if the water level WL around the tank rises during the installation work of the tank 1, the water around the tank flows into the tank 1 via the waste pipe 4 in response to this, and the water level around the tank 1 It is possible to reliably prevent the tank 1 from being lifted by the rise of.
[0015]
And, as in this embodiment, when the tank 1 is partitioned into a plurality of chambers, that is, the ditch 6 and the sedimentation basin 7 by the partition wall 5, a through pipe 8 that communicates the adjacent chambers 6 and 7 is disposed. To do.
In this case, the penetrating tube 8 is disposed at substantially the same height as the discard tube 4.
[0016]
Accordingly, the water around the tank that has flowed into the tank 1 (ditch 6) through the waste pipe 4 is further partitioned by the partition wall 5 through the through pipe 8, and the waste pipe 4 is not provided. It is possible to flow into the first chamber (sedimentation basin 7), and it is possible to more reliably prevent the tank 1 from being lifted due to a rise in the surrounding water level by eliminating the chamber that generates buoyancy.
[0017]
The number and diameter of the discard pipes 4 and the through pipes 8 disposed in the tank 1 and the positions of the pipes can be determined according to the capacity of the tank 1, the expected rising speed of the water level around the tank, and the like.
[0018]
Further, in this embodiment, after the installation work of the waste pipe 4 disposed in the tank 1 is completed, it is not closed and used. However, the through pipe 8 is connected to the sedimentation basin from the ditch 6 by connecting the auxiliary pipe 8a to the upper part. 7 is used as equipment piping for introducing the treatment liquid.
[0019]
When installing (constructing) the tank 1 in the ground 10, a waste pipe 4 having an end opened to the outside of the tank 1 at a position near the bottom of the side wall 3 of the tank 1 is disposed around the tank during the tank installation work. When the water level WL rises, it is arranged so that water flows smoothly into the tank 1, and the tank 1 is further divided into a plurality of chambers, that is, a ditch 6 and a sedimentation basin 7 by a partition wall 5. In this case, a through pipe 8 communicating with the adjacent chambers 6 and 7 is provided, and water around the tank that has flowed into the tank 1 (ditch 6) through the waste pipe 4 is further removed. Through the rise of the surrounding water level by eliminating the chamber that causes buoyancy by flowing into the chamber (sedimentation basin 7) of the tank 1 partitioned by the partition wall 5 and not provided with the waste pipe 4. To prevent tank 1 from floating To.
As a result, it is not necessary to fill the tank 1 with water, and it is possible to cope with an unexpected increase in the water level around the tank, to level the work process, and to improve work efficiency. it can.
[0020]
As described above, the tank lifting prevention method during the installation work of the present invention has been described with reference to an example in which the planar shape partitioned into the two chambers of the ditch 6 and the sedimentation basin 7 is applied to a circular sewage treatment tank made of concrete. The object of application of the method for preventing the tank from rising during the installation work of the invention is not limited to this, and it should be widely applied to large tanks used in various applications made of concrete or metal having a circular or square planar shape. Can do.
[0021]
【The invention's effect】
According to the tank lifting prevention method during the installation work of the present invention, a waste pipe whose end is opened to the outside of the tank is arranged near the bottom of the tank, and the water level around the tank rises during the tank installation work. In the tank lift prevention method during the installation work that allows water to flow into the tank when the installation work is completed, the through pipe that communicates with the adjacent chamber partitioned by the partition wall is installed after the installation work is completed. By connecting an auxiliary pipe to the upper part, the tank is arranged so that it can be used as equipment piping for introducing the processing liquid from one chamber of the tank to the other chamber. By allowing water to flow into each tank, even if the water level around the tank rises during the installation work of the tank, the water around the tank will flow into the tank via the waste pipe. Water level around the tank It is possible to reliably prevent the tank from being lifted by the rise, which can cope with an unexpected rise in the water level around the tank and level the work process, thereby improving work efficiency. The tank can be easily prevented from rising without being lowered.
[0022]
Then, the water around the tank that has flowed into the tank through the discard pipe can be further flowed into each of the plurality of chambers partitioned by the partition wall through the through pipe, and a chamber that generates buoyancy is provided. By eliminating this, it is possible to more reliably prevent the tank from being lifted due to a rise in the surrounding water level, and to connect the through pipe that communicates with the adjacent chamber partitioned by the partition wall after the installation work is completed. By connecting an auxiliary pipe to the upper part of the tank, it can be used as equipment piping for introducing the processing liquid from one chamber of the tank to the other chamber .
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an example of a tank to which a tank floating prevention method during installation work of the present invention is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tank 2 Bottom board 3 Side wall 4 Throwing pipe 5 Partition wall 6 Chamber (ditch)
7 rooms (sedimentation pond)
8 Penetration tube 9 Top panel 10 Ground

Claims (1)

タンクの底部近傍位置に、端部をタンク外に開放した捨て管を配設し、タンクの設置工事中にタンク周辺の水位が上昇したときに、タンク内に水を流入させるようにする設置工事中のタンクの浮き上がり防止方法において、仕切壁により区画されている隣接する室を連通する貫通管を、設置工事完了後、貫通管の上部に補助管を接続することにより、タンクの一方の室から他方の室に処理液を導入する設備配管として利用できるように配設し、該貫通管を介して、区画された複数の室の各々に水を流入させるようにすることを特徴とする設置工事中のタンクの浮き上がり防止方法。Installation work in which a waste pipe with the end open to the outside of the tank is installed near the bottom of the tank so that water flows into the tank when the water level around the tank rises during the tank installation work In the tank lift prevention method, the through pipe that connects the adjacent chambers partitioned by the partition wall is connected to the upper part of the through pipe after the installation work is completed, so that it can be removed from one chamber of the tank. Installation work characterized in that it is arranged so that it can be used as equipment piping for introducing the treatment liquid into the other chamber, and water is allowed to flow into each of a plurality of partitioned compartments through the through pipe. How to prevent the tank inside from rising.
JP07974699A 1999-03-24 1999-03-24 How to prevent tank lift during installation Expired - Fee Related JP4067683B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP07974699A JP4067683B2 (en) 1999-03-24 1999-03-24 How to prevent tank lift during installation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP07974699A JP4067683B2 (en) 1999-03-24 1999-03-24 How to prevent tank lift during installation

Publications (2)

Publication Number Publication Date
JP2000273920A JP2000273920A (en) 2000-10-03
JP4067683B2 true JP4067683B2 (en) 2008-03-26

Family

ID=13698804

Family Applications (1)

Application Number Title Priority Date Filing Date
JP07974699A Expired - Fee Related JP4067683B2 (en) 1999-03-24 1999-03-24 How to prevent tank lift during installation

Country Status (1)

Country Link
JP (1) JP4067683B2 (en)

Also Published As

Publication number Publication date
JP2000273920A (en) 2000-10-03

Similar Documents

Publication Publication Date Title
CN107794954B (en) Anti-floating water leakage pressure relief structure
JP4067683B2 (en) How to prevent tank lift during installation
CN207512815U (en) High-efficient row's silt device
JP5919605B2 (en) Scum remover
KR101674417B1 (en) Drainage system using siphon phenomenon
CN210728768U (en) Surface water discharging device for sedimentation tank
JP4743417B2 (en) Water stop device and method for forming through hole
CN210947063U (en) Municipal administration drainage is with anti-pollution degerming drain pipe
CN220266610U (en) Local precipitation structure in foundation ditch
CN207324175U (en) A kind of environment-friendly sewage sedimentation basin
CN213806871U (en) Seepage-proofing pool drainage system
CN209837071U (en) Damage-free deep foundation pit pipe well operation closed bottom plate structure
CN220888695U (en) Concrete caisson for dewatering in foundation pit
CN110639242A (en) Separation system for tunnel sewage treatment and construction method thereof
JP2007218072A (en) Manhole
CN215562731U (en) Supplementary waterproof basic unit of waterproof construction falls drainage device
CN109811872A (en) Pond automatic hydraulic bottom valve Accrete clearing device and its method
JPS5847835A (en) Discharge switching device for fluid
CN220706601U (en) Underwater fixing structure of sea drainage pipe diffuser
CN211057899U (en) Leachate sewage pool dredging system
CN213836704U (en) Drainage device falls in bottom plate
CN110314426B (en) Surface water draining device and method for sedimentation tank
CN209798977U (en) Automatic hydraulic bottom valve dredging device for water pool
US7160440B2 (en) Storm water separator system
KR880002486Y1 (en) Syphons

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20050328

A711 Notification of change in applicant

Free format text: JAPANESE INTERMEDIATE CODE: A712

Effective date: 20060517

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20070307

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20070904

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20071105

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20080108

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20080109

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110118

Year of fee payment: 3

R150 Certificate of patent or registration of utility model

Free format text: JAPANESE INTERMEDIATE CODE: R150

LAPS Cancellation because of no payment of annual fees